Introduction to pH - acidic and basic (alkaline)

pH can be viewed as an abbreviation for power of Hydrogen - or more completely, power of the concentration of the Hydrogen ionin a liquid.

The mathematical definition of pH is a bit less intuitive but in general more useful. It says that the pH is equal to to the negative logarithmic value of the Hydrogen ion (H+) concentration, or

pH = -log [H+]

pH can alternatively be defined mathematically as the negativelogarithmic valueof the Hydroxonium ion (H3O+) concentration. Using the Bronsted-Lowry approach

pH = -log [H3O+]

pH values are calculated in powers of 10. The hydrogen ion concentration in a solution with pH 1.0 is 10 times larger than the hydrogen concentration in a solution with pH 2.0. The larger the hydrogen ion concentration - the smaller the pH.

when the pH is above 7 the solution is basic (alkaline)

when the pH is below 7 the solution is acidic

In pure neutral water the concentration of hydrogen and hydroxide ions are both 10-7 equivalents per liter.

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